Crystalline form of the compound (s)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol

ABSTRACT

The present invention relates to a crystalline form of the compound (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol.

The present invention relates to a crystalline form of the compound (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol (said compound being hereinafter also referred to as “COMPOUND”).

The preparation of (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol and the medicinal use thereof is described in the published PCT applications WO 2011/007324 and WO 2013/175397. (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol can also be prepared as described below in Example 1.

The aim of the present invention was to provide crystalline forms of COMPOUND, and in particular crystalline forms with advantageous properties. Such advantageous properties may include higher melting points, better flow properties, higher thermodynamic stability, less hygroscopicity, different solubility, higher purity, better reproducibilty in manufacturing (for example better filtration parameters and better reproducibility of formation of the solid), defined morphology, and/or better long-term stability. It has now been found that the crystalline form A of COMPOUND as described herein has advantageous properties.

DESCRIPTION OF THE FIGURES

FIG. 1 shows the X-ray powder diffraction diagram of COMPOUND in the crystalline form A, wherein the X-ray powder diffraction diagram is displayed against Cu Kα1 radiation. In the diagram the angle of refraction 2θ is plotted on the horizontal axis and the counts on the vertical axis. The X-ray diffraction diagram shows peaks having a relative intensity, as compared to the most intense peak in the diagram, of the following percentages (relative peak intensities given in parenthesis) at the indicated angles of refraction 2theta (selected peaks from the range 3-30° 2theta with relative intensity larger than 10% are reported): 4.0° (18%), 4.2° (46%), 5.4° (100%), 8.0° (59%), 8.5° (68%), 9.1° (12%), 10.8° (72%), 12.7° (31%), 13.4° (18%), 13.6° (15%), 14.4° (28%), 16.0° (18%), 17.0° (31%), 17.3° (15%), 17.7° (22%), 19.0° (15%), 19.3° (17%), 20.4° (47%), 21.0° (22%), 21.3° (26%), 21.8° (22%), 22.8° (23%), 25.0° (20%), and 25.5° (19%).

FIG. 2 shows the X-ray powder diffraction diagram of COMPOUND in the crystalline form B, wherein the X-ray powder diffraction diagram is displayed against Cu Kα1 radiation. In the diagram the angle of refraction 2θ is plotted on the horizontal axis and the counts on the vertical axis. The X-ray diffraction diagram shows very broad peaks having a relative intensity, as compared to the most intense peak in the diagram, of the following percentages (relative peak intensities given in parenthesis) at the indicated angles of refraction 2theta (selected peaks from the range 3-30° 2theta with relative intensity larger than 10% are reported): 5.9° (74%), 7.1° (70%), 8.1° (35%), 11.9° (61%), 14.6° (48%), 20.1° (65%), and 21.5° (100%).

FIG. 3 shows the X-ray powder diffraction diagram of COMPOUND in the crystalline form C, wherein the X-ray powder diffraction diagram is displayed against Cu Kα1 radiation. In the diagram the angle of refraction 2θ is plotted on the horizontal axis and the counts on the vertical axis. The X-ray diffraction diagram shows peaks having a relative intensity, as compared to the most intense peak in the diagram, of the following percentages (relative peak intensities given in parenthesis) at the indicated angles of refraction 2theta (selected peaks from the range 3-30° 2theta with relative intensity larger than 10% are reported): 3.7° (11%), 6.4° (55%), 7.4° (100%), 9.8° (77%), 12.8° (49%), 13.2° (28%), 14.7° (15%), 17.0° (24%), 19.5° (24%), 20.5° (22%), 21.2° (19%), 23.3° (17%), and 25.9° (20%).

FIG. 4 shows the X-ray powder diffraction diagram of COMPOUND in the amorphous state, wherein the X-ray powder diffraction diagram is displayed against Cu Kα1 radiation. In the diagram the angle of refraction 2θ is plotted on the horizontal axis and the counts on the vertical axis. The X-ray diffraction shows a typical diagram as obtained for amorphous materials.

For the avoidance of any doubt, the above-listed peaks describe the experimental results of the X-ray powder diffraction shown in FIGS. 1 to 3. It is understood that, in contrast to the above peak list, only a selection of characteristic peaks is required to fully and unambiguously characterise the COMPOUND in the respective crystalline form of the present invention.

DESCRIPTION OF THE INVENTION

1) A first embodiment of the invention relates to a crystalline form, such as an essentially pure crystalline form, of the compound (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol, characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 5.4°, 8.5°, and 10.8°.

2) In another embodiment the present invention relates to the crystalline form according to embodiment 1), characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 4.2°, 5.4°, 8.0°, 8.5°, and 10.8°.

3) In another embodiment the present invention relates to the crystalline form according to embodiment 1), characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 4.2°, 5.4°, 8.0°, 8.5°, 10.8°, 12.7°, 14.4°, 17.7°, 20.4°, and 21.3°.

4) In another embodiment the present invention relates to the crystalline form according to any one of embodiments 1) to 3), which essentially shows the X-ray powder diffraction pattern as depicted in FIG. 1.

5) In another embodiment the present invention relates to the crystalline form according to any one of embodiments 1) to 4), which has a melting point of about 79° C. as determined by differential scanning calorimetry using the method as described herein.

6) In another embodiment the present invention relates to a crystalline form, such as an essentially pure crystalline form, of the compound (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol obtainable by:

-   -   i) dissolving 20 mg of         (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol         in amorphous form in 0.1 mL ethyl acetate;     -   ii) adding 0.9 mL n-heptane gradually over 1 h; and     -   iii) letting it standing closed overnight at 20-25° C.; or     -   iv) mixing 25-30 mg of         (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol         in amorphous form with 5 mL ethyl acetate/n-heptane 1/9 (volume         by volume) and heating to 70° C.; and     -   v) allowing the solution to cool to 20-25° C. and storing it         overnight at 4° C.

7) In another embodiment the present invention relates to the crystalline form according to embodiment 6), characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 5.4°, 8.5°, and 10.8°.

8) In another embodiment the present invention relates to the crystalline form according to embodiment 6), characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 4.2°, 5.4°, 8.0°, 8.5°, and 10.8°.

9) In another embodiment the present invention relates to the crystalline form according to embodiment 6), characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 4.2°, 5.4°, 8.0°, 8.5°, 10.8°, 12.7°, 14.4°, 17.7°, 20.4°, and 21.3°.

10) In another embodiment the present invention relates to the crystalline form according to embodiment 6), which essentially shows the X-ray powder diffraction pattern as depicted in FIG. 1.

11) In another embodiment the present invention relates to the crystalline form according to any one of embodiments 6) to 10), which has a melting point of about 79° C. as determined by differential scanning calorimetry using the method as described herein.

12) In another embodiment the present invention relates to the crystalline form according to any one of embodiments 1) to 5), obtainable by the processes of embodiment 6).

Based on the dependencies of the different embodiments 1) to 12) as disclosed hereinabove, the following embodiments are thus possible and intended and herewith specifically disclosed in individualised form: 1, 2+1, 3+1, 4+1, 4+2+1, 4+3+1, 5+1, 5+2+1, 5+3+1, 5+4+1, 5+4+2+1, 5+4+3+1, 6, 7+6, 8+6, 9+6, 10+6, 11+6, 11+7+6, 11+8+6, 11+9+6, and 11+10+6. Likewise embodiment 12) relates to the following embodiments herewith specifically disclosed in individualised form:

1 obtainable by 6, 2+1 obtainable by 6, 3+1 obtainable by 6, 4+1 obtainable by 6, 4+2+1 obtainable by 6, 4+3+1 obtainable by 6, 5+1 obtainable by 6, 5+2+1 obtainable by 6, 5+3+1 obtainable by 6, 5+4+1 obtainable by 6, 5+4+2+1 obtainable by 6, and 5+4+3+1 obtainable by 6.

In the list above the numbers refer to the embodiments according to their numbering provided hereinabove whereas “+” indicates the dependency from another embodiment. The different individualised embodiments are separated by commas. In other words, “5+4+1” for example refers to embodiment 5) depending on embodiment 4), depending on embodiment 1), i.e. embodiment “5+4+1” corresponds to embodiment 1) further characterised by the features of the embodiments 4) and 5). Moreover, “obtainable by 6” means that the indicated individualised embodiment is obtainable by the processes of embodiment 6).

Definitions provided herein are intended to apply uniformly to the subject matter as defined in any one of embodiments 1) to 12), and, mutatis mutandis, throughout the description and the claims unless an otherwise expressly set out definition provides a broader or narrower definition. It is well understood that a definition or preferred definition of a term or expression defines and may replace the respective term or expression independently of (and in combination with) any definition or preferred definition of any or all other terms or expressions as defined herein.

The term “essentially pure” is understood in the context of the present invention to mean especially that at least 90, preferably at least 95, and most preferably at least 99 per cent by weight of (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol is present in the crystalline form A.

When defining the presence of a peak in e.g. an X-ray powder diffraction diagram, a common approach is to do this in terms of the S/N ratio (S=signal, N=noise). According to this definition, when stating that a peak has to be present in an X-ray powder diffraction diagram, it is understood that the peak in the X-ray powder diffraction diagram is defined by having an S/N ratio of greater than x (x being a numerical value greater than 1), usually greater than 2, especially greater than 3.

In the context with stating that the crystalline form essentially shows an X-ray powder diffraction pattern as depicted in FIG. 1 the term “essentially” means that at least the major peaks of the diagram depicted in said figure, i.e. those having a relative intensity of more than 10%, especially more than 20%, as compared to the most intense peak in the diagram, have to be present. However, the person skilled in the art of X-ray powder diffraction will recognize that relative intensities in X-ray powder diffraction diagrams may be subject to strong intensity variations due to preferred orientation effects.

Unless used regarding temperatures, the term “about” placed before a numerical value “X” refers in the present application to an interval extending from X minus 10% of X to X plus 10% of X, and preferably to an interval extending from X minus 5% of X to X plus 5% of X. In the particular case of temperatures, the term “about” placed before a temperature “Y” refers in the present application to an interval extending from the temperature Y minus 5 ° C. to Y plus 5° C., and preferably to an interval extending from Y minus 3° C. to Y plus 3° C.

When specifying an angle of diffraction 2theta (2θ) for a peak in the present application, it should be understood that the value given is to be understood as an interval from said value minus 0.2° to said value plus 0.2°, and preferably from said value minus 0.1° to said value plus 0.1°.

The crystalline form A of the present invention can be used as medicament, e.g. in the form of pharmaceutical compositions for enteral or parenteral administration, such as especially oral administration, and is suitable for decreasing the number of circulating lymphocytes and for the prevention and/or treatment of a disease or disorder associated with an activated immune system in mammals, such as especially humans.

The production of the pharmaceutical compositions can be effected in a manner which will be familiar to any person skilled in the art (see for example Remington, The Science and Practice of Pharmacy, 21st Edition (2005), Part 5, “Pharmaceutical Manufacturing” [published by Lippincott Williams & Wilkins]) by bringing the crystalline form A of the present invention, optionally in combination with other therapeutically valuable substances, into a galenical administration form together with suitable, non-toxic, inert, pharmaceutically acceptable solid or liquid carrier materials and, if desired, usual pharmaceutical adjuvants.

The crystalline form A of COMPOUND may be used as single component or as mixtures with other crystalline forms or the amorphous form of COMPOUND.

Diseases or disorders associated with an activated immune system which can be treated and/or prevented with the crystalline form A of the present invention are described for example in WO 2011/007324.

Preferred diseases or disorders to be treated and/or prevented with the crystalline form A of the present invention are selected from the group consisting of rejection of transplanted organs such as kidney, liver, heart, lung, pancreas, cornea, and skin; graft-versus-host disease; autoimmune syndromes including Sjogren's syndrome, spondylarthropathy/ankylosing spondylitis, juvenile arthritis, subacute cutaneous lupus, discoid lupus erythematosus, lupus nephritis, systemic sclerosis, diffuse cutaneous systemic sclerosis, vascilitis (e.g. M. Wegener), giant cell arteritis, Behcet disease, non-infectious uveitis,

Goodpasture syndrome, Grave's disease, Guillain Barré syndrome, primary biliary cirrhosis, primary sclerosing cholangitis, autoimmune hepatitis, polymyositits, dermatomyositis, microscopic colitis, celiac disease, sarcoidosis, vitiligo, alopecia areata, chronic inflammatory demyelinating polyneuropathy (CIDP), Rasmussen's encephalitis, rheumatoid arthritis, multiple sclerosis, inflammatory bowel diseases such as Crohn's disease and ulcerative colitis, psoriasis, psoriatic arthritis, thyroiditis such as Hashimoto's thyroiditis, uveo-retinitis, and systemic lupus erythematosus; atopic diseases such as rhinitis, conjunctivitis, and atopic dermatitis; asthma; type I diabetes; and post-infectious autoimmune diseases including rheumatic fever.

Very preferably the crystalline form A of the present invention is used to treat systemic lupus erythematosus.

The present invention also relates to a method for the prevention or treatment of a disease or disorder mentioned herein or mentioned in WO 2011/007324 comprising administering to a subject (especially a human subject) a pharmaceutically active amount of the crystalline form A of the present invention.

Furthermore, the crystalline form A of the present invention is also useful in combination with one or several immunomodulating agents, for the prevention and/or treatment of the diseases and disorders mentioned herein. According to a preferred embodiment of the invention, said agents are selected from the group consisting of immunosuppressants, corticosteroids, nonsteroidal anti-inflammatory drugs, cytotoxic drugs, adhesion molecule inhibitors, cytokines, cytokine inhibitors, cytokine receptor antagonists and recombinant cytokine receptors.

The present invention also relates to the use of the crystalline form A of the present invention for the preparation of a pharmaceutical composition, optionally for use in combination with one or several immunomodulating agents, for the prevention or treatment of the diseases and disorders mentioned herein or mentioned in WO 2011/007324. (S)-3-{4-[5-(2-Cyclopentyl-6-methoxy-pyrid n-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol can be prepared for example as described in the published PCT application WO 2011/007324 (see in particular Example 2) or by using the preparation process as disclosed in the published PCT application WO 2013/175397. In particular the compound can also be prepared as described herein below.

Experimental Part

The following Examples illustrate the invention in more detail. Temperatures are given in degrees Celsius. If not stated otherwise, room temperature is in the range of 18-25° C., and percentages are given by weight.

Abbreviations As Used Herein:

-   a/a area per area -   API active pharmaceutical ingredient -   ca. approximately -   DCM dichloromethane -   DIPEA Hüning's base, diethylisopropylamine -   DMF dimethylformamide -   DMSO dimethylsulfoxide -   DSC differential scanning calorimetry -   eq. equivalent(s) -   EtOAc ethyl acetate -   EtOH ethanol -   Fig. figure -   h hour(s) -   ¹H-NMR hydrogen-1 nuclear magnetic resonance -   HPLC high performance liquid chromatography -   HPMC hydroxypropyl methylcellulose -   LC-MS liquid chromatography - mass spectrometry -   MeOH methanol -   min minute(s) -   m.p. melting point -   RH relative humidity -   rt room temperature

TBTU 2-(1H-benzotriazole-1-yl)-1,2,3,3-tetramethyluronium tetrafluoroborate

-   TEA triethylamine -   TFA trifluoroacetic acid -   THF tetrahydrofuran -   TLC thin layer chromatography -   t_(R) retention time     -   XRPD X-ray powder diffraction

Methods Used: ¹H-NMR

400 MHz, Bruker; chemical shifts are given in ppm relative to the solvent used.

X-ray Powder Diffraction Analysis

X-ray powder diffraction patterns were collected on a Bruker D8 Advance X-ray diffractometer equipped with a Lynxeye detector operated with CuKa-radiation in reflection mode (coupled two Theta/Theta). Typically, the X-ray tube was run at of 40 kV/40 mA. A step size of 0.02° (20) and a step time of 76.8 sec over a scanning range of 3-50° in 2θ were applied. The divergence slit was set to fixed 0.3. Powders were slightly pressed into a silicon single crystal sample holder with depth of 0.5 mm and samples were rotated in their own plane during the measurement. Diffraction data are reported using Cu Kα1 (λ=1.5406 Å), after the Kα2 component has been stripped using the instrument evaluation software (EVA). The accuracy of the 2θ values as provided herein is in the range of +/−0.1-0.2° as it is generally the case for conventionally recorded X-ray powder diffraction patterns.

Differential Scanning Calorimetry (DSC)

DSC data were collected on a Mettler Toledo STARe System (DSC822e module, measuring cell with ceramic sensor and STAR software version 9.20) equipped with a 34 position auto-sampler. The instrument was calibrated for energy and temperature using certified indium. Typically 1-5 mg of each sample, in an automatically pierced aluminium pan, was heated at 10° C. min⁻¹, unless stated otherwise, from −20° C. to 280° C. A nitrogen purge at 20 mL min⁻¹ was maintained over the sample. Peak temperatures are reported for melting points.

EXAMPLE 1 Preparation of (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol a) (R)-N-((2-Cyclopentyl-6-methoxyisonicotinoyl)oxy)-4-((2,2-dimethyl-1,3-dioxolan-4-yl)methoxy)-3-ethyl-5-methylbenzimidamide

To a 30 L reactor is added 2-cyclopentyl-6-methoxy-isonicotinic acid (1.27 kg, 1 eq.; can be prepared e.g. as described in WO 2013/175397), DMF (17 mL) and DCM (18 L). To the suspension is added oxalyl chloride (534 mL, 1.1 eq.) at 20° C. over 30 min. The mixture is stirred for 30 min. The reaction is confirmed complete by LC-MS analysis. A solution of (R)-4-(2,2-dimethyl-[1,3]dioxolan-4-ylmethoxy)-3-ethyl-N-hydroxy-5-methyl-benzamidine (1.77 kg, 1 eq.; can be prepared as described in WO 2011/007324) and TEA (1.78 L, 2.2 eq.) in DCM (4 L) is added to the acid chloride at <30° C. over a period of 20 min. After stirring for 15 min the reaction is confirmed complete by LC-MS analysis. The reaction mixture is washed with water (7 L). Solvent (18 L) is removed at 55° C. and reduced pressure. EtOH (26 L) is added, the suspension cooled to 0° C. and filtered. The filter cake is washed with EtOH (7 L). The solid is dried on a rotary evaporator at 50° C. to yield an off-white solid. Yield: 2261 g (77%). LC-MS: purity: 100% a/a, t_(R)=1.886 min, [M+1]⁺=512; ¹H-NMR (CDCl₃): δ 7.43 (s, 2 H), 7.34 (s, 1 H), 7.12 (s, 1 H), 5.16 (s, 2 H), 4.52 (quint, J=5.8 Hz, 1 H), 4.21 (dd, J₁=8.3 Hz, J₂=6.9 Hz, 1 H), 3.98 (s, 3 H), 3.96 (m, 1 H), 3.83 (m, 2 H), 3.19 (m, 1 H), 2.70 (m, 2 H), 2.33 (s, 3 H), 2.06 (m, 2 H), 1.85 (m, 4 H), 1.71 (m, 2 H), 1.46 (d, J=21.3 Hz, 6 H), 1.25 (t, J=7.6 Hz, 3 H).

b) (R)-5-(2-Cyclopentyl-6-methoxypyridin-4-yl)-3-(4-((2,2-dimethyl-1,3-dioxolan-4-yl)methoxy)-3-ethyl-5-methylphenyl)-1,2,4-oxadiazole

A mixture of (R)-N-((2-cyclopentyl-6-methoxyisonicotinoyl)oxy)-4-((2,2-dimethyl-1,3-dioxolan-4-yl)methoxy)-3-ethyl-5-methylbenzimidamide (2150 g, 1 eq.) in toluene (10 L) is heated to reflux for 4 h. Water is collected in a Dean Stark apparatus. The solution is concentrated to dryness at 70° C. and reduced pressure to yield a yellow oil. Yield: 2116 g (102%). LC-MS: purity: 96% a/a (4% a/a toluene), t_(R)=2.665 min, [M+1]⁺=494; ¹H-NMR (CDCl₃): δ 7.87 (d, J=6.3 Hz, 2 H), 7.50 (s, 1 H), 7.30 (s, 1 H), 4.55 (quint, J=5.8 Hz, 1 H), 4.23 (dd, J₁=8.4 Hz, J₂=6.5 Hz, 1 H), 4.01 (m, 4 H), 3.90 (m, 2 H), 3.24 (m, 1 H), 2.77 (m, 2 H), 2.40 (s, 3 H), 2.09 (m, 2 H), 1.88 (m, 4 H), 1.73 (m, 2 H), 1.50 (s, 3 H), 1.48 (d, J=22.0 Hz, 6 H), 1.32 (t, J=7.5 Hz, 3 H).

LC-MS method used in steps a) and b):

Agilent G1956B (MS, Ionisation: ESI+, APCI), Agilent G1312B Bin Pump, Agilent G1315C DAD, Agilent G1316B (thermostated column compartment), Agilent G1367C (auto sampler). Injection volume: 2μL; Column: Kinetex C18, 2.6 μm, 2.1×50 mm; Temperature: 40° C.; Flow: 1 mL/min; Gradient: Water/Acetonitrile: 95:5 to 5:95 in 2.8 min, then 95:5 in 0.2 min.

c) (S)-3-{4-[5-(2-Cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol

To a 30 L Büchi reactor is added (R)-5-(2-cyclopentyl-6-methoxypyridin-4-yl)-3-(4-((2,2-dimethyl-1,3-dioxolan-4-yl)methoxy)-3-ethyl-5-methylphenyl)-1,2,4-oxadiazole (2.28 kg, 1 eq.) and EtOH (5 L). The solution is heated to 45° C. and 1 N HCI (3 L, 0.75 eq.) is added. The resulting mixture is stirred at 45 ° C. for 1 h and further for 3 h under reduced pressure (400 mbar). The mixture is neutralized with 32% NaOH (300 mL, 0.75 eq.) and concentrated at 60° C. and reduced pressure until the minimum stirring volume is reached (ca. 2 L). The reactor is set to normal pressure with nitrogen. The residue is diluted with EtOAc (20 L). The mixture is washed with water (2×10 L). The organic layer is concentrated at 60° C. and reduced pressure to yield a yellow oil. Yield: 2053 g (98%). A second batch is produced; yield: 1907 g (98%).

Crystallization:

Both batches (2053 g+1907 g) are combined and dissolved in EtOAc (5.5 L) in a Pyrex flask (API solution). To a 30 L reactor is added (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol in crystalline form A (14 g) and n-heptane (30 L). The suspension is heated to 40° C. and the API solution is added over a period of 1 h at 40° C. The suspension is further stirred for 0.5 h, cooled to 20° C. and filtered over a 30 L Büchi nutsche. The product is washed with n-heptane (6 L). The product is dried on the nutsche applying a gentle nitrogen stream for two days.

Yield: 3300 g (83%), Purity (HPLC method): 99.51% a/a; m.p.: about 79 ° C. (DSC), COMPOUND in crystalline form A (FIG. 1).

¹H-NMR (D₆ DMSO): δ 7.78 (s, 2 H), 7.53 (s, 1 H), 7.26 (s, 1 H), 4.98 (d, J=4.6 Hz, 1 H), 4.65 (s, 1 H), 3.94 (s, 3 H), 3.86 (m, 2 H), 3.75 (m, 1 H), 3.50 (t, J =5.4 Hz, 2 H), 3.28 (m, 1 H), 2.75 (d, J=7.5 Hz, 2 H), 2.35 (s, 3 H), 2.03 (m, 2 H), 1.81 (m, 4 H), 1.69 (m, 2 H), 1.22 (t, J=7.5 Hz, 3 H).

HPLC method:

HPLC system Agilent 1100; Injection volume: 5μL; Column: Zorbax Eclipse XDB C18, 3.5 μm, 150 mm×4.6 mm; Temperature: 30° C.; Flow: 1 mL/min; Detection wavelength: 250 nm; Gradient: Water/Acetonitrile: 95:5 to 5:95 in 2.8 min, then 95:5 in 0.2 min. Eluent: Eluent A: water/MeOH/TFA (95/5/0.05), Eluent B: water/MeOH/TFA (5/95/0.05); Gradient: 0-1 min 40% A, 7-22 min 0% A, 22.1-27 min 40% A.

Preparation of amorphous COMPOUND:

Amorphous COMPOUND is obtainable by the process described for Example 2 of the published PCT application WO 2011/007324. Said process is as follows:

a) To a solution of 2-cyclopentyl-6-methoxy-isonicotinic acid (162 mg, 0.732 mmol) in DMF (2 mL) and THF (10 mL), DIPEA (189 mg, 251 μL, 1.46 mmol) followed by TBTU (235 mg, 0.732 mmol) is added. The mixture is stirred at rt for 10 min before (R)-4-(2,2-dimethyl-[1,3]dioxolan-4-ylmethoxy)-3-ethyl-N-hydroxy-5-methyl-benzamidine (226 mg, 0.732 mmol) is added. The mixture is stirred at rt for 1 h before it is diluted with EtOAc and washed with water. The organic layer is separated and concentrated. The residue (375 mg) is dissolved in dioxane (10 mL) and the mixture is heated to 105° C. for 18 h. The mixture is cooled to rt, concentrated and the crude product is purified on preparative TLC plates (silica gel, 0.5 mm) using DCM containing 10% of methanol to give 4-{3-[4-((R)-2,2-dimethyl-[1,3]dioxolan-4-ylmethoxy)-3-ethyl-5-methyl-phenyl]-[1,2,4]oxadiazol-5-yl}-2-cyclopentyl-6-methoxy-pyridine (396 mg) as a yellow oil; LC-MS: t_(R)=1.39 min, [M+H]⁺=494.31.

b) A solution of 4-{3-[4-((R)-2,2-dimethyl-[1,3]dioxolan-4-ylmethoxy)-3-ethyl-5-methyl-phenyl]-[1,2,4]oxadiazol-5-yl}-2-cyclopentyl-6-methoxy-pyridine (390 mg, 790 μmol) in 4 M HCI in dioxane (16 mL) is stirred at rt for 90 min before it is concentrated. The crude product is purified on preparative TLC plates using DCM containing 10% of methanol to give (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol (80 mg) as an off-white foam; LC-MS: t_(R)=1.20 min, [M+H]⁺=454.32; ¹H-NMR (400 MHz, CDCl₃): δ 7.91 (d, J=2.0 Hz, 1 H), 7.89 (d, J=2.0 Hz, 1 H), 7.53 (d, J=0.8 Hz, 1 H), 7.32 (d, J=1.0 Hz, 1 H), 4.16-4.22 (m, 1 H), 4.03 (s, 3 H), 3.96-3.99 (m, 2 H), 3.93 (dd, J₁=4.3 Hz, J₂=11.3 Hz, 1 H), 3.88 (dd, J₁=5.5 Hz, J₂=11.3 Hz, 1 H), 3.21-3.31 (m, 1 H), 2.79 (q, J=7.6 Hz, 2 H), 2.74 (s br, 1 H), 2.43 (s, 3 H), 2.07-2.17 (m, 2 H), 1.85-1.96 (m, 4 H), 1.70-1.81 (m, 2 H), 1.34 (t, J =7.5 Hz, 3 H); XRPD diagram as shown in FIG. 4.

In the above description for the preparation of amorphous COMPOUND the compounds were characterised by ¹H-NMR (Bruker Avance II, 400 MHz UltraShield™, 400 MHz (¹H), 100 MHz (¹³C); chemical shifts are reported in parts per million (ppm) relative to tetramethylsilane (TMS), and multiplicities are given as s (singlet), d (doublet), t (triplet), q (quartet), quint (quintuplet), h (hextet), hept (heptuplet) or m (multiplet), br=broad, coupling constants are given in Hz); and/or by LC-MS Finnigan MSQ™ plus or MSQ™ surveyor (Dionex, Switzerland), with Agilent G4220A pump and AGilent G4212A DAD (Agilent, Switzerland), column: Zorbax RRHD SB-AQ, 1.8 μm, 3.0×20 mm (Agilent);

gradient: 5-95% acetonitrile in water containing 0.04% of trifluoroacetic acid, within 1.2 min, flow: 1.6 mL/min; t_(R) is given in min.

Compounds were purified by preparative TLC glass plates coated with silica gel 60 F₂₅₄ (0.5 mm).

EXAMPLE 2 Preparation of Form A

20 mg of COMPOUND in amorphous form are dissolved in 0.1 mL EtOAc and 0.9 mL n-heptane are added gradually over 1 h. The formed solid is collected after standing closed overnight at 20-25° C. and consists of COMPOUND in the crystalline form A. Alternatively, 25-30 mg of COMPOUND in amorphous form is mixed with 5 mL EtOAc/n-heptane 1/9 (volume by volume) and heated to 70° C. The solution is allowed to cool to 20-25° C. and is then stored overnight at 4° C. The obtained solid is collected and is COMPOUND in the crystalline form A. By DSC a broad endothermic event is observed in the range of about 66° C. to about 88° C., with peak at about 79° C. (m.p. of crystalline form A).

EXAMPLE 3 Preparation of Form B

0.5 g of COMPOUND in the crystalline form A, 2.5 mL DCM and 3 mL n-heptane are mixed and filtered into a petri dish (with diameter of approximately 9 cm). The solution is allowed to evaporate overnight at 20-25° C. The solid residue is collected and dried under vacuum (2 mbar for 1 h). The so obtained solid residue is COMPOUND in the crystalline form B as shown in FIG. 2. By DSC a broad endothermic event is observed in the range of about 44° C. to about 63° C., with peak at about 58° C. (m.p. of crystalline form B).

EXAMPLE 4 Preparation of Form C

In a 15 mL brown glass vial 266 mg of COMPOUND in the crystalline form A and 36 mg of urea are dissolved in 10 mL methanol. The vial is left open at 20-25° C. for evaporation of the solvent. As soon as all solvent is evaporated and latest after 1 week 10 mL water is added and the sample is stirred by magnetic stirring at 20-25° C. for 5 days. The suspension is filtered and the recovered solid is dried at 2 mbar for 1 h. The so obtained solid residue is COMPOUND in the crystalline form C as shown in FIG. 3. By DSC a broad endothermic event is observed in the range of about 30° C. to about 60° C., with peak at about 48° C. (m.p. of crystalline form C).

EXAMPLE 5 Comparison of Hygroscopicity of COMPOUND in Crystalline Forms A, B, and C Method:

Gravimetric vapour sorption (GVS) analysis:

Measurements were performed simoultaneously for the COMPOUND in the crystalline form A, B, and C on a multi sample instrument SPS-100n (Projekt Messtechnik, Ulm, Germany) operated in stepping mode at 25° C. The sample was allowed to equilibrate at 40% RH before starting a pre-defined humidity program (40-0-95-0-95-40% RH, steps of 5% ARH and with a maximal equilibration time of 24 hours per step were applied. About 20 to 30 mg of each sample was used. The hygroscopic classification is done according to the European Pharmacopeia Technical Guide (1999, page 86), i.e., non-hygroscopic: increase in mass is less than 0.2% mass/mass; slightly hygroscopic: increase in mass is less than 2% and equal to or greater than 0.2% mass/mass; hygroscopic: increase in mass is less than 15% and equal to or greater than 2% mass/mass. The mass change between 40% relative humidity and 80% relative humidity in the first adsorption scan is considered.

Form A: <0.2% mass gain: Non-hygroscopic

Form B: 0.5% mass gain: Slightly hygroscopic

Form C: 0.8% mass gain: Slightly hygroscopic

EXAMPLE 6 Capsules Containing 0.5 mg, 1 mg, 2 mg, and 4 mg of COMPOUND in Crystalline Form A

Capsule for oral use Ingredients (mg) 0.5 mg 1 mg 2 mg 4 mg Coated drug substance COMPOUND in crystalline form 0.50 1.00 2.00 4.00 A Methylcellulose 0.05 0.10 0.20 0.40 Sodium lauryl sulfate 0.001 0.002 0.004 0.008 Dipalmitoyl phosphatidylcholine 0.05 0.10 0.20 0.40 Water, purified 5.16 10.31 20.61 41.22 Capsule blend Methylcellulose 0.16 0.30 0.62 1.25 Sodium lauryl sulfate 0.54 1.10 2.17 4.33 Colloidal silicon dioxide 2.49 2.60 2.78 2.67 Mannitol 352.2 368.8 388.8 368.5 Capsules filling weight (mg) 356 374 397 382

Due to very low aqueous solubility (about 0.06 μg/mL in water) and poor wetting ability of the active substance (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol, the drug substance is coated as a first step. To that extend, methylcellulose (METHOCEL™ A15 Premium LV, suspending agent), sodium lauryl sulfate and dipalmitoyl phosphatidylcholine (wetting agents) are added one after the other to purified water under stirring: each excipient is added only after complete dissolution of the former one. The API, i.e. COMPOUND in crystalline form A, is sieved through mesh size 40, added to the methocel solution and stirred for 3 h, until a complete homogenious suspension is formed. The suspension is spray dried (outlet air temperature 40-50° C., drying gas flow rate 110 kg/h, atomization N₂ gas flow rate 8 kg/h, N₂ atomization pressure 0.7 bar), which results in the coated API. The coating leads to an increase of the solubility of the active substance (about 29 μg/mL in water).

Once coated, the drug substance content is determined in the coated drug substance and the amount of material used in the next step eventually corrected accordingly.

The coated API is sieved together with methylcellulose (METHOCEL™ A15 Premium LV), sodium lauryl sulfate and a part of mannitol (EMPROVE® Parteck® M 200 Mannitol) and mixed. More mannitol portions are added after sieving to the blend in 2 steps, each time followed by mixing. The colloidal silicon dioxide (AEROSIL® 200) is then sieved together with the remainder of the mannitol and added to the powder blend. The final mixture is further blended. The powder is then filled in size “0”, white-opaque HPMC capsules) (VCaps+®). 

1. A crystalline form of the compound (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol, characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 5.4°, 8.5°, and 10.8°.
 2. The crystalline form according to claim 1, characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 4.2°, 5.4°, 8.0°, 8.5°, and 10.8°.
 3. The crystalline form according to claim 1, characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 4.2°, 5.4°, 8.0°, 8.5°, 10.8°, 12.7°, 14.4°, 17.7°, 20.4°, and 21.3°.
 4. The crystalline form according to any one of claims 1 to 3, which essentially shows the X-ray powder diffraction pattern as depicted in FIG.
 1. 5. The crystalline form according to any one of claims 1 to 4, which has a melting point of about 79° C. as determined by differential scanning calorimetry.
 6. A crystalline form of the compound (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol obtainable by: i) dissolving 20 mg of (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol in amorphous form in 0.1 mL ethyl acetate; ii) adding 0.9 mL n-heptane gradually over 1 h; and iii) letting it standing closed overnight at 20-25° C.; or iv) mixing 25-30 mg of (S)-3-{4-[5-(2-cyclopentyl-6-methoxy-pyridin-4-yl)-[1,2,4]oxadiazol-3-yl]-2-ethyl-6-methyl-phenoxy}-propane-1,2-diol in amorphous form with 5 mL ethyl acetate/n-heptane 1/9 (volume by volume) and heating to 70° C.; and v) allowing the solution to cool to 20-25° C. and storing it overnight at 4° C.
 7. The crystalline form according to claim 6, characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 5.4°, 8.5°, and 10.8°.
 8. The crystalline form according to claim 6, characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 4.2°, 5.4°, 8.0°, 8.5°, and 10.8°.
 9. The crystalline form according to claim 6, characterised by the presence of peaks in the X-ray powder diffraction diagram at the following angles of refraction 2θ: 4.2°, 5.4°, 8.0°, 8.5°, 10.8°, 12.7°, 14.4°, 17.7°, 20.4°, and 21.3°.
 10. The crystalline form according to claim 6, which essentially shows the X-ray powder diffraction pattern as depicted in FIG.
 1. 11. The crystalline form according to any one of claims 6 to 10, which has a melting point of about 79° C. as determined by differential scanning calorimetry.
 12. The crystalline form according to any one of claims 1 to 5, obtainable by the processes of claim
 6. 13. A pharmaceutical composition comprising the crystalline form according to any one of claims 1 to 12 and a pharmaceutically acceptable carrier.
 14. The crystalline form according to any one of claims 1 to 12, or a pharmaceutical composition according to claim 13, for use as a medicament.
 15. The crystalline form according to any one of claims 1 to 12, or a pharmaceutical composition according to claim 13, for use in the prevention or treatment of a disease or disorder associated with an activated immune system.
 16. The crystalline form according to any one of claims 1 to 12, or a pharmaceutical composition according to claim 13, for use in the prevention or treatment of a disease or disorder selected from the group consisting of rejection of transplanted organs such as kidney, liver, heart, lung, pancreas, cornea, and skin; graft-versus-host disease; autoimmune syndromes including Sjögren's syndrome, spondylarthropathy/ankylosing spondylitis, juvenile arthritis, subacute cutaneous lupus, discoid lupus erythematosus, lupus nephritis, systemic sclerosis, diffuse cutaneous systemic sclerosis, vascilitis (e.g. M. Wegener), giant cell arteritis, Behcet disease, non-infectious uveitis, Goodpasture syndrome, Grave's disease, Guillain Barrŕ syndrome, primary biliary cirrhosis, primary sclerosing cholangitis, autoimmune hepatitis, polymyositits, dermatomyositis, microscopic colitis, celiac disease, sarcoidosis, vitiligo, alopecia areata, chronic inflammatory demyelinating polyneuropathy (CIDP), Rasmussen's encephalitis, rheumatoid arthritis, multiple sclerosis, inflammatory bowel diseases such as Crohn's disease and ulcerative colitis, psoriasis, psoriatic arthritis, thyroiditis such as Hashimoto's thyroiditis, uveo-retinitis, and systemic lupus erythematosus; atopic diseases such as rhinitis, conjunctivitis, and atopic dermatitis; asthma; type I diabetes; and post-infectious autoimmune diseases including rheumatic fever.
 17. The crystalline form according to any one of claims 1 to 12, or a pharmaceutical composition according to claim 13, for use in the treatment of systemic lupus erythematosus. 